Thermistor imbedded therapeutic catheter

Abstract

A system and method for determining native cardiac output of a heart while maintaining operation of an intracardiac blood pump includes determining a current drawn by the pump motor, a blood pressure within the ascending aorta, and a change in the blood temperature based on a thermodilution technique. An intracardiac blood pump positioned in the aorta includes at least one sensor for determining a motor current and blood pressure and a thermistor for determining the change in blood temperature after a precise fluid bolus has been introduced into the vasculature. A processor receives current, pressure, and temperature measurements, and calculates a pump flow output and a total cardiac output from which the native cardiac output is calculated. The native cardiac output and other clinically relevant variables derived from the measurements inform decisions related to continued therapeutic care, including increasing or decreasing cardiac assistance provided by the intracardiac pump.

1 - 11 . (canceled) 
     
     
         12 . A system for measuring performance of a beating heart of a patient, comprising:
 an intracardiac blood pump assembly comprising an intracardiac blood pump and configured to be displaceably placed in vasculature of a patient;   a thermistor carried by the intracardiac blood pump assembly that is configured to detect blood temperature of the blood flowing in the heart's ascending aorta when the intracardiac blood pump assembly is positioned in the aorta of the patient;   a first sensor carried by the intracardiac blood pump and configured to detect changes in motor current of a motor of the intracardiac blood pump during operation of the intracardiac blood pump;   a second sensor carried by the intracardiac blood pump and configured to detect blood pressure within the ascending aorta when the intracardiac blood pump assembly is positioned in the aorta of the patient; and   a processor configured to:
 receive a first signal from the first sensor, the first signal being indicative of a change in the motor current, receive a second signal from the second sensor, the second signal being indicative of the blood pressure within the ascending aorta, and receive a third signal from the thermistor indicative of a temperature of blood flowing in the heart's ascending aorta, 
 calculate a pump flow output based on the first signal and the second signal, wherein the pump flow output is indicative of a cardiac assistance provided by the intracardiac blood pump, 
 calculate a total cardiac output based on the third signal, wherein the total cardiac output comprises (a) the cardiac assistance provided by the intracardiac blood pump and (b) a native cardiac output of the beating heart, and 
 calculate the native cardiac output of the beating heart during operation of the intracardiac blood pump based on the pump flow output and the total cardiac output. 
   
     
     
         13 . The system of  claim 12 , wherein the third signal indicates a change in temperature of blood flowing into the heart caused by a bolus of fluid introduced into vasculature of the patient at a location that is upstream from the intracardiac blood pump, wherein the introduced bolus of fluid is at an initial temperature that is different than a physiologic blood temperature. 
     
     
         14 . The system of  claim 12 , wherein the third signal indicates a change in temperature of blood flowing near or through openings of a cannula of the intracardiac blood pump. 
     
     
         15 . The system of  claim 12 , wherein the processor is configured to determine the total cardiac output by detecting changes in the third signal as a function of time. 
     
     
         16 . The system of  claim 12 , wherein the processor is configured to calculate the native cardiac output by subtracting the pump flow output from the total cardiac output. 
     
     
         17 . The system of  claim 12 , wherein the thermistor is disposed on a distal end region of a catheter of the intracardiac blood pump assembly. 
     
     
         18 . The system of  claim 12 , wherein the processor is further configured to calculate from the first, second, and third signals at least one of a global end-diastolic volume, an intrathoracic blood volume, an intrathoracic thermal volume, a pulmonary thermal volume, a cardiac index, a stroke volume, an extravascular lung water, a cardiac power output, and a global ejection fraction. 
     
     
         19 . The system of  claim 12 , wherein the processor is further configured to display the native cardiac output on a display screen. 
     
     
         20 . The system of  claim 12 , wherein the processor is further configured to record and store the native cardiac output and to display a history of the native cardiac output as a function of time. 
     
     
         21 . The system of  claim 20 , wherein the processor is further configured to determine a native trend based on the history of the native cardiac output, wherein the native trend indicates whether the native cardiac output is improving with time. 
     
     
         22 . The system of  claim 21 , wherein the processor is further configured to display the native trend on a display screen. 
     
     
         23 . The system of  claim 12 , wherein the processor is configured to calculate the pump flow output by accessing a lookup table that provides a flow rate that is the pump flow output for a given motor current and detected pressure. 
     
     
         24 . The system of  claim 12 , wherein the thermistor is positioned proximal to a proximal end of the intracardiac blood pump. 
     
     
         25 . The system of  claim 12 , wherein the thermistor is imbedded in a catheter of the intracardiac blood pump assembly. 
     
     
         26 . The system of  claim 12 , wherein the intracardiac blood pump assembly further comprises a sheath for delivering the intracardiac blood pump to the patient's heart. 
     
     
         27 . The system of  claim 26 , wherein the thermistor is imbedded in the sheath. 
     
     
         28 . The system of  claim 26 , wherein the sheath comprises a first lumen and a second lumen, the first lumen is sized for delivery of the intracardiac blood pump and the second lumen is sized for delivery of the thermistor.